AT&T must be keeping a close eye on T-Mobile's UnCarrier campaign, because it's starting to tweak its plans as well. AT&T is dropping its off-contract prices, changing its base costs for each data tier and adding a new choice to its Next plans.

As of right now, AT&T's plans are organized in such a way that per-smartphone costs go down as data plans go up -- and customers still pay that same amount after their contract expires. But with the new changes, smartphones can be added to a plan for a flat rate of $40 each. If the contract expires, AT&T automatically takes $15 off each phone.

The base cost for each data tier has changed as well -- the higher the data tier, the higher the discount. For instance, the old base rate for 1GB was $40, but the new rate is $45 while the 20GB tier went from a $200 base rate to $150.

Here's a chart of the new base rates. You'll notice there's a new 8GB plan, by the way:

Data Tier

Old Base Rate

New Base Rate

Old Per Smartphone

New Per Smartphone (Contract)

300MB

$20

$20

$50

$40

1GB

$40

$45

$45

$40

2GB

$50

$55

$45

$40

4GB

$70

$70

$40

$40

6GB

$90

$80

$35

$40

8GB

N/A

$90

N/A

$40

10GB

$120

$100

$30

$40

15GB

$160

$130

$30

$40

20GB

$200

$150

$30

$40

30GB

$300

$225

$30

$40

40GB

$400

$300

$30

$40

50GB

$500

$375

$30

$40

As far as Next plans go, AT&T is adding an extra option. Right now, customers can pay their phones off over a 20-month period and upgrade after one year, but the new option allows them to pay phones off over a 26-month period and upgrade at the 18-month mark.

Also, basic phone prices have dropped from $30 to $20.

T-Mobile may have really started something with its UnCarrier strategy as other carriers start bringing prices down. It eliminated contracts for reduced cell phone plans in March and introduced an early phone upgrade program in July. Then, in October, it started offering a free unlimited international text and data plan.

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